Performance of 18FDG-PET in the management of non-metastatic HIV+ anal squamous cell carcinoma (ASCC).

Abstract

541 Background: ASCC remains rare, but the incidence has been increasing over the last decade, especially in patients with HIV infection (HIV+). A recent meta-analysis demonstrated the usefulness of 18FDG-PET in initial staging and response assessment in ASCC. HIV+ patients may develop opportunistic infections which can cause false positives lymph nodes on PET scanning and, therefore, our objective was to evaluate performance of 18FDG-PET in HIV+ patients. Methods: Retrospective analysis of consecutive patients with non-metastatic ASCC, treated in our institution during six years. HIV+ patients were analyzed separately in two groups according to their lymph nodes status, group 1 (Gr 1): N0, group 2 (Gr 2): N1, N2, N3. Results: A total of 87 patients with ASCC were analyzed, including 24 HIV+ patients (21 males, median age was 53 for male and 50 for women). There were 15 patients in Gr 1 and 9 in Gr 2. All patients performed conventional imaging (MRI and CT-scan). In Gr 1, 12/15 patients had 18FDG-PET, it resulted in upstaging nodal disease in 2 patients. In Gr 2, 6/9 patients had 18FDG-PET, it resulted in upstaging nodal disease in 1 patient and downstaging nodal disease in 2 patients. Both of sensibility and specificity of FDG-PET were 83% in our HIV+ population. All patients underwent Mitomycine C and 5FU based chemoradiation or exclusive radiation therapy. Mean radiation dose received was 63.3Gy in G1 and 63.9Gy in G2. 18FDG-PET drives a modification in treatment strategy in only 1 patient in both of groups. Post-treatment 18FDG-PET was performed 4 months after treatment completion. Among patients who had post-treatment 18FDG-PET, a metabolic complete response was observed in 6/11 patients in Gr 1 and 3/5 patients in Gr 2. Survival at 5 years was 89% and 75% in Gr 1 and Gr 2, respectively. Conclusions: Based on our experience, 18FDG-PET drives substantial changes neither in staging nor in therapeutic strategy for ASCC HIV+ patients, however, it may be useful for radiation therapy planning.